This invention relates to an underwater dive vehicle of the type which may be used for propelling divers to underwater locations, and more particularly to a powered underwater dive vehicle in which the buoyancy may be reduced as the vehicle descends to greater depths in the water, and in which water leakage into sealed compartments of the vehicle is minimized or eliminated.
Small powered underwater dive vehicles for taking one or two divers to underwater locations usually comprise a motor having a drive shaft which is operably connected to a propeller, a battery for energizing the motor and a control switch for selectively energizing the motor. Such devices are illustrated and described, for example, in U.S. Pat. Nos. 5,379,714, 4,864,959 and 4,996,938. Such vehicles, however, have encountered problems of buoyancy and leakage. Leakage is a particular problem when the vehicle is taken to substantial depths where the pressure maybe several atmospheres. For every 10 meters of descent in sea water, an additional atmosphere of pressure is placed on the vehicle and its parts. Thus, at a depth of 30 meters or approximately 100 feet, there are 3 atmospheres of pressure, and the pressure corresponding increases as greater depths are attained. Underwater dive vehicles should be designed to withstand 15 atmospheres of pressure or the pressure that would be encountered at a depth of 500 feet.
The greater the pressure, the more stress there is on the seals which are in place to keep water out of such areas as the buoyancy chambers, the housings surrounding the batteries and the motor. U.S. Pat. No. 4,864,959 recognizes this problem and is directed to detecting leaks of sea water into the battery or motor compartments of underwater dive vehicles. That patent also suggests that water absorbing sheets be stuffed around mechanical parts and the battery and clutch compartments. Another moisture detection system for an underwater dive vehicle is disclosed in U.S. Pat. No. 4,996,938.
Another problem with underwater dive vehicles has to do with the buoyancy of the vehicle. It is highly desirable that at the surface the vehicle have a positive buoyancy so that the unattended vehicle may float on the surface and preferably also support a diver at the surface. However, during the dive, the operator of the vehicle should not be constantly fighting buoyancy.
It is thus an object of the present invention to provide a solution to the water leaks which have heretofore plagued underwater dive vehicles by so constructing the vehicle that the water tight seals are not placed under stress even when the vehicle submerges to depths of several hundred feet.
It is another object of this invention to provide an underwater vehicle the frame of which is open to the water and which thus eliminates any pressure on the frame.
It is a further object of this invention to provide an underwater dive vehicle that has a positive buoyancy at the water surface but which buoyancy may be automatically reduced as the vehicle is taken to greater depths.
It is an additional object of this invention to provide an underwater dive vehicle that has an easily adjustable buoyancy which will permit the vehicle selectively to float at the surface of the water, to reduce its buoyancy as the vehicle is descending in the water, to remain at a neutral buoyancy at any selected depth, and to reduce or increase the buoyancy at any time during the dive.